HBASE-26649 Support meta replica LoadBalance mode for RegionLocator#g… #4078
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huaxiangsun
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Hi @Apache9, please review backport as there are some difference between master and branch-2, thanks. |
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Apache9
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Jan 30, 2022
| @@ -53,6 +54,8 @@ | |||
| import org.slf4j.Logger; | |||
| import org.slf4j.LoggerFactory; | |||
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| import static org.apache.hadoop.hbase.client.RegionLocator.LOCATOR_META_REPLICAS_MODE; | |||
| if (conn != null) { | ||
| try { | ||
| try (Table metaTable = getMetaHTable(conn)) { | ||
| numOfReplicas = metaTable.getDescriptor().getRegionReplication(); |
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Ah, this is a bit painful... We used to expect getMetaScan to only contain memory operations but here we will have network io... And everytime we call this method it will generate a rpc calll...
Looking at the code above, in the async code we also have this and we even introduce a blocking rpc call. I haven't realized this when reviewing the PR for master, but obviously it is incorrect, we should not do blocking call in the async code. We should try to find a better way...
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Nice find! Let me back out the master changes.
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I reverted the commit to the master. You are right, the network call is bad. How about changing getMetaScan from a static method to a non-static one, so it can use a cached meta Replica count? Need to handle the case that meta replica count is changed dynamically.
…etAllRegionLocations() Signed-off-by: Duo Zhang <[email protected]>
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…etAllRegionLocations()
Signed-off-by: Duo Zhang [email protected]